The present invention generally relates to detection of chemical, biological, radioactive, and other substances by a light scattering probe and a chemical sensor.
Light scattering techniques such as Raman spectroscopy are known to be capable of identifying chemicals and biological agents. A major limitation associated with Raman spectroscopy is that the Raman scattering signals from chemicals and biological agents tend to be very weak. Although many attempts have been made to increase Raman scattering intensity, such efforts have not yielded practical and economical detectors based on Raman spectroscopy. As a result, Raman scattering so far only has very limited applications in sensing chemicals and biological agents.
A specific need for high sensitivity spectral sensing has arisen recently in the area of food safety. Many of the food products that are contaminated with or illegitimately mixed with harmful substances which may not have colors or smells that can be easily detected in the field such as grocery stores and food distribution centers. Although sophisticated analyses can be conducted in central chemical labs, but the testing methods are too costly and have too long a turn-around times to be feasible for food inspection and safety monitoring in high volume and high throughput commercial food industry.
A need therefore exists for effective and practical Raman spectroscopy based detectors for trace amount of chemical, biological, radioactive, and other substances.